Allah tells us that despite all the clear signs and irrefutable evidence Musa came with, only a few offspring from Fir`awn's followers believed in him. They were even scared that Fir`awn and his followers would force them to return to Kufr (disbelief). Fir`awn was an evil tyrant and extremely arrogant. His people feared him and his power too much. Al-`Awfi reported that Ibn `Abbas said:

﴿فَمَآ ءامَنَ لِمُوسَى إِلاَّ ذُرِّيَّةٌ مِّن قَوْمِهِ عَلَى خَوْفٍ مِّن فِرْعَوْنَ وَمَلَئِهِمْ أَن يَفْتِنَهُمْ﴾

(But none believed in Musa except the offspring of his people because of the fear of Fir `awn and his chiefs, lest they should persecute them.) "The offspring that believed in Musa from Fir`awn's people, other than Banu Israel, were few. Among them were Fir`awn's wife, the believer who was hiding his faith, Fir`awn's treasurer, and his wife.'' The Children of Israel, however, themselves believed in Musa, all of them. They were glad to see him coming. They knew of his description and the news of his advent from their previous Books. They knew that Allah was going to save them through him from the capture of Fir`awn and give them power over him. So when this knowledge reached Fir`awn he was very wary. But his caution and weariness didn't help him one bit. When Musa arrived, Fir`awn subjected them to great harm, and

﴿قَالُواْ أُوذِينَا مِن قَبْلِ أَن تَأْتِيَنَا وَمِن بَعْدِ مَا جِئْتَنَا قَالَ عَسَى رَبُّكُمْ أَن يُهْلِكَ عَدُوَّكُمْ وَيَسْتَخْلِفَكُمْ فِى الاٌّرْضِ فَيَنظُرَ كَيْفَ تَعْمَلُونَ ﴾

(They said: "We (Children of Israel) suffered troubles before you came to us, and since you have come to us.'' He said: "It may be that your Lord will destroy your enemy and make you successors on the earth, so that He may see how you act')﴿7:129﴾ The fact that all of the Children Israel became believers is evidenced by the following Ayat:

﴿وَقَالَ مُوسَى يقَوْمِ إِن كُنتُمْ ءامَنْتُمْ بِاللَّهِ فَعَلَيْهِ تَوَكَّلُواْ إِن كُنْتُم مُّسْلِمِينَ ﴾

فَقَالُواْ عَلَى اللَّهِ تَوَكَّلْنَا رَبَّنَا لاَ تَجْعَلْنَا فِتْنَةً لّلْقَوْمِ الظَّـلِمِينَ- وَنَجّنَا بِرَحْمَتِكَ مِنَ الْقَوْمِ الْكَـفِرِينَ-﴾

(84. And Musa said: "O my people! If you have believed in Allah, then put your trust in Him if you are Muslims.'') (85. They said: "In Allah we put our trust. Our Lord! Make us not a trial for the folk who are wrongdoers.) (86. "And save us by Your mercy from the disbelieving folk.'')